One of my outings while in Minneapolis this past summer was a visit to Minnehaha Falls with a hike along the creek at the bottom of the falls. I knew from hiking this path before that there were some interesting sandstone walls along the creek where people have used their hands or sticks to carve into the soft sandstone. One could call it “scratchiti,” which is graffiti that is scratched or etched into a surface rather than drawn or painted.
This natural formation is referred to as “St. Peter sandstone,” and is very soft easily crumbles into fine sand. Here’s something crazy to consider: St. Peter sandstone is a geological formation from the “Ordovician” period from the Paleozoic Era, approximately 485 million years ago! But the carvings and scratchiti are more recent, of course – there are records of people leaving their marks in this way here only as far back as 1865. Check out this one below: someone made the shape of a small face in the sandstone, as opposed to all of the line-like markings around it.
I found it interesting that at one point in the late 1800s, entrepreneurs scratched off sand and bottled it to sell as souvenirs. Minnehaha sand bottles had become a known and notable souvenir, even as far away as the East Coast. However, in 1889, the Minneapolis Park Board took charge of the area and prohibited this practice, as all of the sand being removed put holes in the bluffs and was damaging the area.
So why is it called “St. Peter Sandstone?” It seems it was named by David Dale Owen (1807-1860), a prominent American geologist who conducted the first geological surveys of Minnesota, Indiana, Kentucky, Arkansas, Wisconsin, and Iowa. It was named after the St. Peter River, which was later renamed the Minnesota River.
